1. Field of the Invention
Exemplary embodiments relate to an apparatus and a method for transmitting/receiving broadcast data, and more particularly, to an apparatus and a method for transmitting/receiving broadcast data in a digital broadcasting system.
2. Description of Related Art
A digital TV transmission scheme based on the ATSC standard that is a terrestrial digital broadcasting system adopted in USA, Canada, Mexico, Korea, or the like, has been known as facilitating an implementation of a transceiver and having excellent economical efficiency. The transmission scheme, which is a single carrier amplitude modulation vestigial side-band (VSB) scheme, transmits high-quality video, audio, and auxiliary data at a single bandwidth of 6 MHz. The most significant feature of the transmission scheme is a modulation scheme. Similarly to the existing analog VSB scheme, the transmission scheme symbolizes digital signals to perform the VSB modulation and uses a 8-VSB modulation scheme in the case of terrestrial broadcasting.
FIGS. 1 and 2 illustrate block diagrams of a transmitting and receiving system in a digital broadcasting system based on the existing ATSC scheme.
FIG. 1 is a block diagram of a transmitting system in a digital broadcasting system in accordance with the related art. In order to transmit data in the transmitting system, a randomizer 110 first randomizes data and a Reed-Solomon encoder 120 performs Reed-Solomon encoding that attaches 20 RS addition bytes to each packet of randomized data. The Reed-Solomon encoded data are interleaved in an interleaver 130 and the interleaved data is trellis-encoded in a trellis encoder 140. The block diagram of FIG. 1 briefly illustrates transmitting devices. The signals output from the trellis encoder 140 are mapped to bit symbols, which are assumed to be 8-level symbols having level values of {−7, −5, −3, −1, +1, +3, +5, +7}. A multiplexer (MUX) 150 inserts data segment synchronization and data field synchronization in a data frame. The multiplexed data are input to a VSB modulator. The VSB modulator 160 receives a pilot and the 8-level trellis data including synchronization to perform the 8-VSB, wherein a sample rate of the VSB modulator 160 is 10.76 Msymbol/s. The signals modulated as described above are output through a transmitting antenna 170.
FIG. 2 is a block diagram of a receiving system in the existing digital broadcasting system. As illustrated in the block diagram, components for demodulating and decoding received signals in the receiving system correspond to each component of the transmitting system. First, when the signals are received through the receiving antenna 270, the VSB demodulator 260 demodulates the modulated signals by the VSB scheme. Next, an equalizer 250 removes an influence of a multi-path channel through which the broadcast signals passes, thereby reducing inter-symbol interference. The signals passing through the equalizer are recovered into an original data form by passing through a trellis decoder 240, a deinterleaver 230, a Reed-Solomon decoder 220, and a derandomizer 210.
The ATSC scheme has high noise margin characteristics to stably provide services and has very high robustness against impulse noises by performing RS encoding and interleaver processes. However, a terrestrial digital broadcasting system adopted in Europe (DVB-T) or Japan (ISDB-T) may selectively apply various transmission capacities, if necessary. On the other hand, in the ATSC scheme, the transmission capacity is fixed. Therefore, a need exists for a technology development of increasing transmission efficiency while maintaining backward compatibility with the existing scheme so as to use the advantages of the ATSC scheme.